1. Field of the Invention
This invention is generally directed to safety guards for use with power hand tools and especially those such as rotary grinders and sanders incorporating a rotating disc. More particularly, the present invention is directed to movable guards which are pivotable relative to a rotating disc of a power hand tool for purposes of providing a safety barrier to prevent injury, both by accidental contact with the rotating disc and also due to debris being thrown beyond the disc.
2. Brief Description of the Related Art
Heretofore there have been many innovations made with respect to providing safety guards for use with hand held power tools which incorporate rotating mechanisms such as sanders, edgers, planars, grinders and the like. Generally, such guards fall into one of two categories. The first type of guard is designed to protectively cover at least a portion of either side of a rotating tool, such as a sander or grinder, such that the guard has opposite sidewalls which extend in parallel relationship with respect to one another on either side of a segment of the disc. The guards are mounted to enclose a portion of the tool disc but must leave a portion of the disc exposed for allowing an edge of the disc to engage a work surface. With some such guards, the guard housing is fixed, however, in others, the guard housing may include a segment which can be pivotable about an axis which is generally parallel to a rotational axis of the disc thereby allowing the guard to move by engagement with a surface, so as to pivot away from the surface and expose an edge portion of the disc.
Some examples of the first type of guard are disclosed in U.S. Pat. Nos. 2,384,243 to Flohr et al., 3,969,856 to Zerrer, 3,585,980 to Mellor, 4,711,055 to Mickos, 5,033,192 to Franz and 5,140,754 to Martenson.
Of the foregoing safety devices, each is designed to be mounted so as to at least partially enclose a rotating disc such that a section of an edge of the disc may be used to engage a work surface. In each of these patents, it is generally the radial edge of the disc which is the working portion of the tool.
In U.S. Pat. Nos. 3,585,980 and 5,033,192, the protective guards or hoods are generally designed to be fixed relative to the rotating tool and provide exit or exhaust openings for guiding material to an appropriate collection device. The guards with respect to these mechanisms are not designed to completely cover the working surface of the tool, and thus, a portion of the tool surface can be accidentally engaged.
In U.S. Pat. No. 5,140,754, the guard is designed to be pivoted about the rotational axis of the tool. Again, it is generally the radial edge of the tool which is the working component of the tool, and even though the guard may be pivoted to allow different portions of the tool surface to be covered, the surface of the tool remains partially unprotected during tool use. A similar operating characteristic is found in U.S. Pat. No. 3,969,856.
In U.S. Pat. Nos. 2,384,243 and 4,711,055, the guards provide a complete enclosure for the rotating disc. Portions of the enclosure are movable or pivotable about a central pivot axis in the event the guard engages a work surface. With these structures, the rotating disc remains within the confines of the guard until the guard engages a surface at which time the guard pivots to allow exposure of a radial edge of the disc. Unfortunately, such guards only find use in specific type of tools wherein the radial edge of the tool is the only working surface of the tool.
A second type of protective guard for rotating tools of the hand held type includes a guard shield which extends in a plane which is generally perpendicular to an elongated axis of a tool body so as to be interposed in a plane parallel to the operating plane of the working tool and the operator or a hand grip of the tool. Such shielding guards normally are somewhat fixed structures which cover only a segment or portion of the rotating disc, leaving a separate section of the disc uncovered. These types of guards or shields are more appropriately used for grinders and sanders wherein a planar face of the grinder or sander, as well as a radial edge of the tool, may be used on a work surface. Examples of these types of guards are disclosed in U.S. Pat. No. 4,330,967 to Richardson and German Patent DE 3940584A1.
Unfortunately, there remains a need to provide better protective guards or shields for use with hand held rotary tools of the type which have a working surface which may be a planar surface or a radial edge of the tool, such as the case with many grinders and rotary sanders. Further, there remains a need to provide such guards which will, in many working positions of the tool, provide an effectively complete cover or shield between the tool and an operator and yet which will pivot to enable the tool to be used in hard to reach areas which might otherwise be prohibited, if the guard or shield remain fixed relative to the tool during its operation.
The present invention is directed to a pivotable guard assembly which may be used in conjunction with conventional fixed guards or may be incorporated with a fixed guard segment in order to provide as much shielding protection to a tool operator as is possible when using a powered rotating tool, such as a power sander or power grinder. The invention incorporates a collar or mounting sleeve which can be mounted along a front portion of a body of a hand held power tool and secured thereto and to which is pivotably mounted a guard or shield member. In preferred embodiments, the guard or shield member is designed to extend, when in a first position, generally parallel to a rotating disc of the tool so as to provide a barrier over at least substantially half of the disc. The pivotable guard or shield has an outer portion extending beyond the radial edge of the disc and an inner portion which is contoured so as to allow pivotable movement of the guard or the shield relative to the front portion of the body of the power tool without interference therewith. In this respect, the inner edge of the guard or shield will generally be somewhat concavely configured to permit adequate clearance so that the guard can be pivoted from its first position, in covering relationship with respect to the tool disc, to a second fully withdrawn position, wherein the guard or shield extends generally perpendicular to a plane of rotation of the disc.
In a preferred embodiment, the pivotal guard is made of a transparent material to allow the operator to view the working tool therethrough to better control the use of the tool when working on a surface.
Also, in preferred embodiments, the manner in which the pivotal guard or shield is mounted to the mounting collar is such as to provide a resilient return of the pivotal guard or shield to its first fully covering position. In this manner, the pivotal guard will be automatically pivoted away from the working disc when the pivotal guard engages a surface which would otherwise block the disc from reaching a work surface to thereof allow contact of the disc with the work surface. This is particularly the case when the disc must be used in corner areas. As the disc approaches a corner, the guard or shield will be pivoted toward the second position but will resiliently return to its first covering position in the event the tool is moved away from the closely confining space or area in which the tool is being used, thus providing maximum safety and coverage for the working disc which allows access to restricted work areas.
In another embodiment of the invention, a second generally fixed guard or shield may be mounted directly to the tool body or to the mounting collar by way of which the pivotal guard or shield is connected to the work tool.
In yet another embodiment of the invention, the guard of the present invention may include a first generally fixed section and a second pivotal section which is pivotally mounted relative to the first section such that the fixed and pivotal sections fully cover a rotating disc when in a first position generally parallel relative to a rotary place of the working disc. A pivot attachment between the pivotal guard section and the fixed may be such that the pivotal guard section is directly connected to the fixed guard section such as by resilient hinges which permit the pivotal section to move from the first parallel covering position toward and to a fully withdrawn position generally perpendicular to the working or rotary plane of a disc. The hinges automatically return the pivotal guard section to the fully covering or first position as soon as the tool is removed from a restricted work space. In some embodiments, both the fixed and the pivotal guard sections may be transparent and in some embodiments, one or more of the guard sections may include outwardly extending flanges for providing further protection along the rachet edge portion of a disc.
Also, in some embodiments, a friction locking mechanism may be provided so as to normally retain the pivotal section of the guard or shield in its first position until sufficient pressure is applied to pivot the guard away from its fully covering position. Such friction retention devices will provide added safety by ensuring that the mere movement of the tool by the operator will not cause a pivotal movement of the shield until the shield engages a surface which is obstructing the use of the tool and which surface contact will in effect provide the necessary force to overcome the friction lock and cause the pivotal movement of the pivotal section of the guard assembly.
It is a primary object of the present invention to provide a safety guard or shield for use with hand held rotary power tools, such as power grinders and power sanders, wherein the guard includes at least one pivotable component which is generally resiliently loaded to maintain the guard section in a fully covering position in a plane extending generally parallel to a tool disc and between a plane of the disc and the handle of the tool but which is pivotal away to allow the tool disc to engage hard to reach areas so that the guard shield does not provide an obstruction prohibiting the normal use of the disc of the power tool.
It is yet a further object of the present invention to provide a safety guard or shield for use with power grinders and power sanders, as well as other power tools having rotary discs wherein at least a portion of the guard or shield is transparent so as to allow an operator to view the working tool and a work surface therethrough.